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incubator-nuttx/binfmt/libelf/libelf_bind.c

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/****************************************************************************
* binfmt/libelf/libelf_bind.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <inttypes.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/elf.h>
#include <nuttx/kmalloc.h>
#include <nuttx/binfmt/elf.h>
#include <nuttx/binfmt/symtab.h>
#include "libelf.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* CONFIG_DEBUG_FEATURES, CONFIG_DEBUG_INFO, and CONFIG_DEBUG_BINFMT have to
* be defined or CONFIG_ELF_DUMPBUFFER does nothing.
*/
#if !defined(CONFIG_DEBUG_INFO) || !defined (CONFIG_DEBUG_BINFMT)
# undef CONFIG_ELF_DUMPBUFFER
#endif
#ifdef CONFIG_ELF_DUMPBUFFER
# define elf_dumpbuffer(m,b,n) binfodumpbuffer(m,b,n)
#else
# define elf_dumpbuffer(m,b,n)
#endif
/****************************************************************************
* Private Types
****************************************************************************/
struct elf_symcache_s
{
dq_entry_t entry;
Elf_Sym sym;
int idx;
};
typedef struct elf_symcache_s elf_symcache_t;
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: elf_readrels
*
* Description:
* Read the (ELF_Rel structure * buffer count) into memory.
*
****************************************************************************/
static inline int elf_readrels(FAR struct elf_loadinfo_s *loadinfo,
FAR const Elf_Shdr *relsec,
int index, FAR Elf_Rel *rels,
int count)
{
off_t offset;
int size;
/* Verify that the symbol table index lies within symbol table */
if (index < 0 || index > (relsec->sh_size / sizeof(Elf_Rel)))
{
berr("Bad relocation symbol index: %d\n", index);
return -EINVAL;
}
/* Get the file offset to the symbol table entry */
offset = sizeof(Elf_Rel) * index;
size = sizeof(Elf_Rel) * count;
if (offset + size > relsec->sh_size)
{
size = relsec->sh_size - offset;
}
/* And, finally, read the symbol table entry into memory */
return elf_read(loadinfo, (FAR uint8_t *)rels, size,
relsec->sh_offset + offset);
}
/****************************************************************************
* Name: elf_readrelas
*
* Description:
* Read the (ELF_Rela structure * buffer count) into memory.
*
****************************************************************************/
static inline int elf_readrelas(FAR struct elf_loadinfo_s *loadinfo,
FAR const Elf_Shdr *relsec,
int index, FAR Elf_Rela *relas,
int count)
{
off_t offset;
int size;
/* Verify that the symbol table index lies within symbol table */
if (index < 0 || index > (relsec->sh_size / sizeof(Elf_Rela)))
{
berr("Bad relocation symbol index: %d\n", index);
return -EINVAL;
}
/* Get the file offset to the symbol table entry */
offset = sizeof(Elf_Rela) * index;
size = sizeof(Elf_Rela) * count;
if (offset + size > relsec->sh_size)
{
size = relsec->sh_size - offset;
}
/* And, finally, read the symbol table entry into memory */
return elf_read(loadinfo, (FAR uint8_t *)relas, size,
relsec->sh_offset + offset);
}
/****************************************************************************
* Name: elf_relocate and elf_relocateadd
*
* Description:
* Perform all relocations associated with a section.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
static int elf_relocate(FAR struct elf_loadinfo_s *loadinfo, int relidx,
FAR const struct symtab_s *exports, int nexports)
{
FAR Elf_Shdr *relsec = &loadinfo->shdr[relidx];
FAR Elf_Shdr *dstsec = &loadinfo->shdr[relsec->sh_info];
FAR Elf_Rel *rels;
FAR Elf_Rel *rel;
FAR elf_symcache_t *cache;
FAR Elf_Sym *sym;
FAR dq_entry_t *e;
dq_queue_t q;
uintptr_t addr;
int symidx;
int ret;
int i;
int j;
rels = kmm_malloc(CONFIG_ELF_RELOCATION_BUFFERCOUNT * sizeof(Elf_Rel));
if (rels == NULL)
{
berr("Failed to allocate memory for elf relocation\n");
return -ENOMEM;
}
dq_init(&q);
/* Examine each relocation in the section. 'relsec' is the section
* containing the relations. 'dstsec' is the section containing the data
* to be relocated.
*/
ret = OK;
for (i = j = 0; i < relsec->sh_size / sizeof(Elf_Rel); i++)
{
/* Read the relocation entry into memory */
rel = &rels[i % CONFIG_ELF_RELOCATION_BUFFERCOUNT];
if (!(i % CONFIG_ELF_RELOCATION_BUFFERCOUNT))
{
ret = elf_readrels(loadinfo, relsec, i, rels,
CONFIG_ELF_RELOCATION_BUFFERCOUNT);
if (ret < 0)
{
berr("Section %d reloc %d: "
"Failed to read relocation entry: %d\n",
relidx, i, ret);
break;
}
}
/* Get the symbol table index for the relocation. This is contained
* in a bit-field within the r_info element.
*/
symidx = ELF_R_SYM(rel->r_info);
/* First try the cache */
sym = NULL;
for (e = dq_peek(&q); e; e = dq_next(e))
{
cache = (FAR elf_symcache_t *)e;
if (cache->idx == symidx)
{
dq_rem(&cache->entry, &q);
dq_addfirst(&cache->entry, &q);
sym = &cache->sym;
break;
}
}
/* If the symbol was not found in the cache, we will need to read the
* symbol from the file.
*/
if (sym == NULL)
{
if (j < CONFIG_ELF_SYMBOL_CACHECOUNT)
{
cache = kmm_malloc(sizeof(elf_symcache_t));
if (!cache)
{
berr("Failed to allocate memory for elf symbols\n");
ret = -ENOMEM;
break;
}
j++;
}
else
{
cache = (FAR elf_symcache_t *)dq_remlast(&q);
}
sym = &cache->sym;
/* Read the symbol table entry into memory */
ret = elf_readsym(loadinfo, symidx, sym);
if (ret < 0)
{
berr("Section %d reloc %d: Failed to read symbol[%d]: %d\n",
relidx, i, symidx, ret);
kmm_free(cache);
break;
}
/* Get the value of the symbol (in sym.st_value) */
ret = elf_symvalue(loadinfo, sym, exports, nexports);
if (ret < 0)
{
/* The special error -ESRCH is returned only in one condition:
* The symbol has no name.
*
* There are a few relocations for a few architectures that do
* no depend upon a named symbol. We don't know if that is the
* case here, but we will use a NULL symbol pointer to indicate
* that case to up_relocate(). That function can then do what
* is best.
*/
if (ret == -ESRCH)
{
berr("Section %d reloc %d: "
"Undefined symbol[%d] has no name: %d\n",
relidx, i, symidx, ret);
}
else
{
berr("Section %d reloc %d: "
"Failed to get value of symbol[%d]: %d\n",
relidx, i, symidx, ret);
kmm_free(cache);
break;
}
}
cache->idx = symidx;
dq_addfirst(&cache->entry, &q);
}
if (sym->st_shndx == SHN_UNDEF && sym->st_name == 0)
{
sym = NULL;
}
/* Calculate the relocation address. */
if (rel->r_offset < 0 ||
rel->r_offset > dstsec->sh_size - sizeof(uint32_t))
{
berr("Section %d reloc %d: Relocation address out of range, "
"offset %" PRIdPTR " size %jd\n",
relidx, i, (uintptr_t)rel->r_offset,
(uintmax_t)dstsec->sh_size);
ret = -EINVAL;
break;
}
addr = dstsec->sh_addr + rel->r_offset;
/* Now perform the architecture-specific relocation */
ret = up_relocate(rel, sym, addr);
if (ret < 0)
{
berr("ERROR: Section %d reloc %d: Relocation failed: %d\n",
relidx, i, ret);
break;
}
}
kmm_free(rels);
while ((e = dq_peek(&q)))
{
dq_rem(e, &q);
kmm_free(e);
}
return ret;
}
static int elf_relocateadd(FAR struct elf_loadinfo_s *loadinfo, int relidx,
FAR const struct symtab_s *exports, int nexports)
{
FAR Elf_Shdr *relsec = &loadinfo->shdr[relidx];
FAR Elf_Shdr *dstsec = &loadinfo->shdr[relsec->sh_info];
FAR Elf_Rela *relas;
FAR Elf_Rela *rela;
FAR elf_symcache_t *cache;
FAR Elf_Sym *sym;
FAR dq_entry_t *e;
dq_queue_t q;
uintptr_t addr;
int symidx;
int ret;
int i;
int j;
relas = kmm_malloc(CONFIG_ELF_RELOCATION_BUFFERCOUNT * sizeof(Elf_Rela));
if (relas == NULL)
{
berr("Failed to allocate memory for elf relocation\n");
return -ENOMEM;
}
dq_init(&q);
/* Examine each relocation in the section. 'relsec' is the section
* containing the relations. 'dstsec' is the section containing the data
* to be relocated.
*/
ret = OK;
for (i = j = 0; i < relsec->sh_size / sizeof(Elf_Rela); i++)
{
/* Read the relocation entry into memory */
rela = &relas[i % CONFIG_ELF_RELOCATION_BUFFERCOUNT];
if (!(i % CONFIG_ELF_RELOCATION_BUFFERCOUNT))
{
ret = elf_readrelas(loadinfo, relsec, i, relas,
CONFIG_ELF_RELOCATION_BUFFERCOUNT);
if (ret < 0)
{
berr("Section %d reloc %d: "
"Failed to read relocation entry: %d\n",
relidx, i, ret);
break;
}
}
/* Get the symbol table index for the relocation. This is contained
* in a bit-field within the r_info element.
*/
symidx = ELF_R_SYM(rela->r_info);
/* First try the cache */
sym = NULL;
for (e = dq_peek(&q); e; e = dq_next(e))
{
cache = (FAR elf_symcache_t *)e;
if (cache->idx == symidx)
{
dq_rem(&cache->entry, &q);
dq_addfirst(&cache->entry, &q);
sym = &cache->sym;
break;
}
}
/* If the symbol was not found in the cache, we will need to read the
* symbol from the file.
*/
if (sym == NULL)
{
if (j < CONFIG_ELF_SYMBOL_CACHECOUNT)
{
cache = kmm_malloc(sizeof(elf_symcache_t));
if (!cache)
{
berr("Failed to allocate memory for elf symbols\n");
ret = -ENOMEM;
break;
}
j++;
}
else
{
cache = (FAR elf_symcache_t *)dq_remlast(&q);
}
sym = &cache->sym;
/* Read the symbol table entry into memory */
ret = elf_readsym(loadinfo, symidx, sym);
if (ret < 0)
{
berr("Section %d reloc %d: Failed to read symbol[%d]: %d\n",
relidx, i, symidx, ret);
kmm_free(cache);
break;
}
/* Get the value of the symbol (in sym.st_value) */
ret = elf_symvalue(loadinfo, sym, exports, nexports);
if (ret < 0)
{
/* The special error -ESRCH is returned only in one condition:
* The symbol has no name.
*
* There are a few relocations for a few architectures that do
* no depend upon a named symbol. We don't know if that is the
* case here, but we will use a NULL symbol pointer to indicate
* that case to up_relocate(). That function can then do what
* is best.
*/
if (ret == -ESRCH)
{
berr("Section %d reloc %d: "
"Undefined symbol[%d] has no name: %d\n",
relidx, i, symidx, ret);
}
else
{
berr("Section %d reloc %d: "
"Failed to get value of symbol[%d]: %d\n",
relidx, i, symidx, ret);
kmm_free(cache);
break;
}
}
cache->idx = symidx;
dq_addfirst(&cache->entry, &q);
}
if (sym->st_shndx == SHN_UNDEF && sym->st_name == 0)
{
sym = NULL;
}
/* Calculate the relocation address. */
if (rela->r_offset < 0 ||
rela->r_offset > dstsec->sh_size)
{
berr("Section %d reloc %d: Relocation address out of range, "
"offset %" PRIdPTR " size %jd\n",
relidx, i, (uintptr_t)rela->r_offset,
(uintmax_t)dstsec->sh_size);
ret = -EINVAL;
break;
}
addr = dstsec->sh_addr + rela->r_offset;
/* Now perform the architecture-specific relocation */
ret = up_relocateadd(rela, sym, addr);
if (ret < 0)
{
berr("ERROR: Section %d reloc %d: Relocation failed: %d\n",
relidx, i, ret);
break;
}
}
kmm_free(relas);
while ((e = dq_peek(&q)))
{
dq_rem(e, &q);
kmm_free(e);
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: elf_bind
*
* Description:
* Bind the imported symbol names in the loaded module described by
* 'loadinfo' using the exported symbol values provided by 'symtab'.
*
* Returned Value:
* 0 (OK) is returned on success and a negated errno is returned on
* failure.
*
****************************************************************************/
int elf_bind(FAR struct elf_loadinfo_s *loadinfo,
FAR const struct symtab_s *exports, int nexports)
{
#ifdef CONFIG_ARCH_ADDRENV
int status;
#endif
int ret;
int i;
/* Find the symbol and string tables */
ret = elf_findsymtab(loadinfo);
if (ret < 0)
{
return ret;
}
/* Allocate an I/O buffer. This buffer is used by elf_symname() to
* accumulate the variable length symbol name.
*/
ret = elf_allocbuffer(loadinfo);
if (ret < 0)
{
berr("elf_allocbuffer failed: %d\n", ret);
return ret;
}
#ifdef CONFIG_ARCH_ADDRENV
/* If CONFIG_ARCH_ADDRENV=y, then the loaded ELF lies in a virtual address
* space that may not be in place now. elf_addrenv_select() will
* temporarily instantiate that address space.
*/
ret = elf_addrenv_select(loadinfo);
if (ret < 0)
{
berr("ERROR: elf_addrenv_select() failed: %d\n", ret);
return ret;
}
#endif
/* Process relocations in every allocated section */
for (i = 1; i < loadinfo->ehdr.e_shnum; i++)
{
/* Get the index to the relocation section */
int infosec = loadinfo->shdr[i].sh_info;
if (infosec >= loadinfo->ehdr.e_shnum)
{
continue;
}
/* Make sure that the section is allocated. We can't relocated
* sections that were not loaded into memory.
*/
if ((loadinfo->shdr[infosec].sh_flags & SHF_ALLOC) == 0)
{
continue;
}
/* Process the relocations by type */
if (loadinfo->shdr[i].sh_type == SHT_REL)
{
ret = elf_relocate(loadinfo, i, exports, nexports);
}
else if (loadinfo->shdr[i].sh_type == SHT_RELA)
{
ret = elf_relocateadd(loadinfo, i, exports, nexports);
}
if (ret < 0)
{
break;
}
}
#if defined(CONFIG_ARCH_ADDRENV)
/* Ensure that the I and D caches are coherent before starting the newly
* loaded module by cleaning the D cache (i.e., flushing the D cache
* contents to memory and invalidating the I cache).
*/
#if 0 /* REVISIT... has some problems */
up_addrenv_coherent(&loadinfo->addrenv);
#else
up_coherent_dcache(loadinfo->textalloc, loadinfo->textsize);
up_coherent_dcache(loadinfo->dataalloc, loadinfo->datasize);
#endif
/* Restore the original address environment */
status = elf_addrenv_restore(loadinfo);
if (status < 0)
{
berr("ERROR: elf_addrenv_restore() failed: %d\n", status);
if (ret == OK)
{
ret = status;
}
}
#else
/* Ensure that the I and D caches are coherent before starting the newly
* loaded module by cleaning the D cache (i.e., flushing the D cache
* contents to memory and invalidating the I cache).
*/
up_coherent_dcache(loadinfo->textalloc, loadinfo->textsize);
up_coherent_dcache(loadinfo->dataalloc, loadinfo->datasize);
#endif
return ret;
}
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